Functional agglomerated speckles and methods for manufacturing such speckles

ABSTRACT

Functional agglomerated speckles, for incorporation in dentifrices, include agglomerates of a water insoluble powdered functional material and a mixture of a water insoluble, ethanol soluble ethyl cellulose binder and a suitable water soluble binder, such as polyvinyl pyrrolidone. Such speckles, while more &#34;soluble&#34; or disintegrable in a flavored dentifrice than those based on ethyl cellulose binders without PVP, still can satisfactorily maintain their integrity and identity during processing of the dentifrice after addition of the speckles to the main dentifrice body, but on storage, after packaging of the dentifrice in dispensing tubes, they will soften sufficiently so as then to be essentially impalpable to one utilizing the dentifrice in brushing his teeth. Despite such softening the speckles continue to maintain their identity as separate small bodies in the dentifrice. The invented speckles are especially useful in translucent or transparent gel dentifrices, which contain components, such as flavoring and surface active agents, which may controllably soften the speckles on storage. Also described in the specification are dentifrices incorporating the present speckles, methods for manufacturing the speckles and such dentifrices, and such dentifrices packaged in end use dispensing containers.

This application is a division of co-pending U.S. patent applicationSer. No. 307,272, filed Sept. 30, 1981, now U.S. Pat. No. 4,376,762,granted Mar. 15, 1983.

This invention relates to functional agglomerated speckles forincorporation in dentifrices. More particularly, it relates to suchspeckles and to dentifrices containing them, wherein the speckles aremade from a water insoluble powdered functional material, such as adental polishing agent, a water insoluble, ethanol soluble ethylcellulose binder, and a suitable water soluble binder, such as polyvinylpyrrolidone. The invention also relates to methods for manufacturingsuch speckles and such dentifrices and to such dentifrices packaged indispensing containers, such as transparent or translucent containers,through the wall of which the speckles, in a transparent or translucentgel dentifrice, may be viewed. To obtain desired visual effects thespeckles will usually be of a color which contrasts with the rest of thedentifrice.

Prior art toothpastes and gels which incorporated contrastingly coloredspeckles are shown. Although such speckles in some cases are primarilyfor aesthetic effects, they may be based on functional components, suchas polishing agents, and they can perform desired functions in thedentifrice, in addition to making it of attractive appearance. Variouscolors and combinations thereof in the speckles may serve to identifythe particular type of dentifrice, such as fluoride and non-fluoridedentifrices. Incorporation of reactive materials in the speckles canhelp to prevent reaction or premature reaction with other dentifricecomponents. When the speckles comprise mostly water insoluble material,such as a polishing agent, they can be present in a transparent ortranslucent gel dentifrice without objectionably clouding the gel. Thus,the gel remains clear, with the speckles being visible therein, and thespeckles provide a decorative and aethestically improved appearance forthe product.

In the past various speckled dentifrices have included speckles whichwere initially palpable but became impalpable during toothbrushing.Although such products have met with technical approval it has also beenfound desirable to market another type of speckled dentifrice, like thatof this invention, in which the speckles, although readily visible anddiscrete, are impalpable initially, and subsequently during brushing ofthe teeth.

Among the various prior art references showing dentifrices incorporatingspeckles and other similar dispersed solids therein, the closest to thepresent invention that are known to applicants are U.S. Pat. Nos. Re.29,634; 3,929,988; 4,003,971; 4,089,943; and 4,220,552. The reissuepatent describes a dentifrice containing visible and palpable,substantially water-insoluble, agglomerated particles of polishingagents. Binding agents are employed in the manufacture of the describedspeckles, and among the water soluble binders methyl cellulose and PVPare mentioned. However, methyl cellulose and PVP are water soluble andtherefore do not provide a speckle which will always sufficiently andeasily maintain its integrity during lengthy processing and alsoeventually soften to an impalpable unit on storage in a dentifrice. U.S.Pat. No. 3,929,988 relates to a dentifrice containing encapsulatedsweetener. Ethyl cellulose is mentioned among various other materialsuseful for coating the sweetener to make the capsules or spheres, whichmay be visible or "micro-size", and are dispersed in the dentifrice.U.S. Pat. No. 4,003,971 teaches making dentifrice speckles and describesthe advantages of water insoluble binders for such speckles. The patentmentions the use of gums as water insoluble binders but does notdisclose or suggest ethyl cellulose. U.S. Pat. No. 4,089,943 teachestoothpaste formulations having dispersed therein visible agglomeratedparticles of dental polishing agent. The advantages of both watersoluble and water insoluble agglomerating or binding agents arementioned in the patent, PVP is disclosed and mixtures of water solubleand water insoluble binders in the speckles are suggested, but ethylcellulose is not mentioned as being useful as a binder. Finally, U.S.Pat. No. 4,220,552 teaches microencapsulation of sodium fluoride bylower alkyl cellulose, such as ethyl cellulose, and dispersing of thecapsules in a dentifrice. The patent does not relate to agglomerates andthe employment of ethyl cellulose as an encapsulating agent does notmake obvious its present use with PVP to make an agglomerating agentuseful in making the present speckles.

The present invention is one wherein ethyl cellulose, which is waterinsoluble but ethanol soluble, and a water soluble binder, preferablyPVP, are utilized together to make an agglomerating agent for afunctional water insoluble powdered material which is made intodentifrice speckles of improved properties. Prior speckles, made withwater soluble binders, such as methyl cellulose or PVP, coulddisintegrate during processing after mixing in with other dentifricecomponents, such as those in previously formulated gel or paste media,if the speckled dentifrice was held too long in the processingequipment, which can happen, as when mechanical breakdowns of processingequipment occur. Such losses of integrity of the speckles could takeplace because such dentifrices contain water, which can solubilize thewater soluble binders of the speckles and lead to separation of thecomponent particles of the speckles. The dissolving of the binder can beminimized in such cases by prompt processing but when filling lineholdups cause processing times to be increased losses of product couldresult. Dentifrice speckles made with ordinary water insoluble bindingagents, as disclosed in the art (such art does not disclose ethylcellulose), when dispersed in dentifrice gels or pastes, tend to bepalpable, and although that may often be desirable, in some dentifrices,e.g., those intended for use by persons with sensitive gingiva, it isnot. The combination of ethyl cellulose and PVP employed as a binder forfunctional speckles in accordance with the present inventionsatisfactorily maintains the integrity of the speckles in aqueousdentifrice media for a sufficiently long time to allow processing afterincorporation of the speckles in the dentifrice. Yet, apparently due tothe presence of PVP, which tends to dissolve in water, and because ofthe action of components of the dentifrice, such as flavoring agents,and in some cases, surface active agents, which tend to soften the ethylcellulose of the speckles on storage, the speckles in the dentifrice maybe softened sufficiently during storage so that, although they maintaintheir integrity and independence and their distinctly separateappearance until they are used, they are impalpable and are readilydisintegrated during toothbrushing. In this respect the speckles of thisinvention function like those described in U.S. Pat. No. 4,376,763,granted Mar. 15, 1983 on application Ser. No. 307,273, filed Sept. 30,1981, in which ethyl cellulose is the water insoluble binder for thespeckles. However, the PVP makes the speckles more useful in dentifricescontaining lesser proportions of flavoring agents (and dental detergentand any other solvents or lipophiles) or in those dentifrices in whichsuch materials are of lower solubilizing (for ethyl cellulose)properties.

In accordance with the present invention functional agglomeratedspeckles, for incorporation in dentifrices, comprise agglomerates ofwater insoluble powdered functional material, a water insoluble, ethanolsoluble ethyl cellulose binder and a water soluble binder. Preferably,the functional material is a dental polishing agent and comprises 75 or80 to 98% of the speckles, the water soluble binder is PVP and thecombination of ethyl cellulose and PVP comprises 2 to 20% of thespeckles. Optionally, the speckles may include a coloring agent, whichmay be 0 to 5% thereof, more preferably 0.05 to 1%, when present. Alsoclaimed in this application are a dentifrice containing such speckles,methods for the manufacture of the speckles and of the dentifrice, and apackaged gel dentifrice containing the invented speckles dispersedtherein.

The invention will be readily understood from the present specification,including the detailed description therein. However, in accordance withthe Statute and Rules of Practice a drawing of a packaged dentifrice ofthis invention is also provided and the figure thereof will bedescribed.

The functional agglomerated speckles are comprised of two essentialcomponents, a water insoluble powdered functional material and acombination of a water insoluble, ethanol soluble ethyl cellulose binderand a water soluble binder. Henceforth in this specification, forclarity and because PVP is a preferred water soluble binder, it willoften be recited instead of "water soluble binder" but such designationis intended to refer to all suitable water soluble binders that can atleast partially replace it in the invented speckles, while the desiredproperties of the speckles will still be obtained. Some other suchbinders will be listed later herein. The water insoluble powderedfunctional material may be characterized as the functional bodying agentand the ethyl cellulose-PVP combination is called the binder. Variousfunctional materials, all of which are preferably water insoluble, or atleast, slowly soluble, can be employed, including colorants, such aspigments, germicides, ion exchange agents, polymeric materials (whichmay contain other active components, sometimes water soluble materials),and flavorings, but it is highly preferred that the functional basematerial for the speckles be a polishing agent or include a majorproportion thereof. Of the polishing agents, normally utilized in drypowder form to make the agglomerated speckles, those preferred are saltsor oxides, such as dicalcium phosphate, tricalcium phosphate, insolublesodium metaphosphate, alumina, silica, magnesium carbonate, calciumcarbonate, calcium pyrophosphate, bentonite and zirconium silicate, andsuitable mixtures thereof. Both anhydrous or calcined forms of thesematerials, such as calcined alumina, and hydrated forms, such asdicalcium phosphate dihydrate, may be employed but the anhydrous orcalcined materials are often preferred. Because the agglomerates willnormally desirably be opaque there is no need to match refractiveindices with those of the dentifrice vehicles (including othercomponents, too) but "transparent" polishing agents, with such amatching refractive index, e.g., 1.44 to 1.47, may be used to maketransparent or translucent speckles, and they may also be employed tomake clear gel dentifrice bodies containing polishing agent. Such"transparent" polishing agents include colloidal silicas and those soldunder the trademark Syloid, as Syloids 63, 65, 72 and 74, under the markSantocel, as Santocel 100 and as Zeo's 49, 113 and 119 and Zeodent.Also, synthetic alkali metal aluminosilicate complexes may beparticularly useful, because they have refractive indices close to thoseof dental vehicles including water, glycerol, sorbitol and gellingagent, which materials are normally employed in the manufacture ofdentifrices.

The water insoluble, powdered functional material utilized to make thepresent speckles will normally be of initial particle sizes in the rangeof 0.5 to 20 microns, preferably being within the range of 1 to 10microns, and more preferably of 2 to 8 microns. However, in someinstances larger particles sizes may be employed, as when theagglomerating operation tends to size-reduce some of the powder, as mayhappen in mixing before actual agglomerating begins.

The water insoluble component of the binding agent for the presentspeckles is ethyl cellulose. This effective binder is soluble inethanol, and is gradually soluble in an aqueous glycerol-sorbitol mediumwhich also contains "solvents" for it, such as flavorings andsurfactants, which are usually present in the dentifrices of thisinvention. Such ethyl cellulose will usually have an ethoxy content inthe range of about 45 to 50%, preferably 48 to 50% or 48 to 49.5%. In apreferred ethyl cellulose, such as that marketed by The Dow ChemicalCompany under the trade name Ethocel Standard 10 Premium EthylCellulose, the ethoxyl content is in the range of 48.0 to 49.5%; theviscosity is 9 to 11 centipoises; the moisture content is 2% maximum;chloride content, as NaCl, is 0.15% maximum; and ash content is 0.15%maximum. The test methods employed for the foregoing analyses are thoseincorporated in Test D914 of the American Society For Testing Materials(ASTM). Because the ethyl cellulose is intended for oral use the maximumcontent of arsenic, as As₂ O₃, is three parts per million (p.p.m.), thatof lead is 10 p.p.m. and that of heavy metal is 40 p.p.m., all by FoodChemicals Codex (FCC) testing.

In the 18-page Dow Chemical Company booklet entitled ETHOCELEthylcellulose Resins-Tough, Rugged Coatings, Adhesives, Hot Melts,copyrighted 1974, 1975 and 1978, hereby incorporated by reference,suitable ethyl cellulose resins for use as binders for the presentspeckles are described. Ethyl cellulose is supplied commercially as awhite to light tan granular powder of a degree of etherification suchthat there are 2.25 to 2.58 ethoxy groups per anhydroglucose unit, whichcorresponds to 45.0 to 49.5% ethoxy content (by weight). Of two gradesof ethyl cellulose commercially available the "standard" materials,which are preferred for the practice of the present invention, haveethoxy contents in the range of 48.0 to 49.5% (by weight), and the lesspreferred "medium" materials have ethoxy contents in the 45.0 to 46.5%range. Of course, such products are available in different viscosityranges, usually from 3 to 110 centipoises, with the medium materialtending to be more viscous.

The standard grade of ethyl cellulose tends to be soluble in aromatichydrocarbons, hydroaromatic hydrocarbons, chlorinated aliphatichydrocarbons and naval stores. It is also soluble in monohydricaliphatic alcohols, such as ethanol; monohydric cyclic alcohols, such asbenzyl alcohol, phenyl ethyl alcohol and pine oil; ether alcohols, suchas glycol ethers; ethers, such as diethyl cellosolve; esters, especiallyacetates, such as isopropyl acetate and sec-amyl acetate, and esters ofhydroxy acids, such as methyl salicylate; and ketones, such ascyclohexanone and acetophenone. Generally, the medium ethoxy grade ofethyl cellulose is less soluble than the standard grade and so may bemore suited for use with PVP when greater proportions of solubilizingmaterials are present in the dentifrice formula. However, in some suchinstances one could use the standard ethyl cellulose alone as a binder,as is taught in the Barth-Norfleet U.S. Pat. No. 4,376,763, previouslymentioned.

Among other physical properties of ethyl cellulose are: a specificgravity of about 1.1; a water absorption after twenty-four hoursimmersion of about 1%; an impact strength, expressed as energy to break,of about 1 to 12 ft. lbs./sq. in. of notch; a tensile strength of about6,000 to 9,000 lbs./sq. in.; an elongation of about 10 to 40%; aRockwell hardness of about 70 to 110; a compression molding temperatureof about 320° to 350° F.; a compression molding pressure of about 300 to6,000 lbs./sq. in.; and a specific heat of about 0.3 to 0.46. Ethylcellulose is heat stable, light stable, colorless, odorless andtasteless.

The water soluble binders which are useful for making the combinationbinder utilized for production of the speckles of this inventioninclude, among others, gum acacia; gelatin; starches, both natural andmodified; alkali metal carboxymethyl celluloses, particularly sodiumcarboxymethyl cellulose; polyethylene glycols; sugars, such as glucoseand sucrose; methyl cellulose; carboxyethyl hydroxyethyl celluloses;alginates, particularly sodium alginate; polyvinyl alcohol; carrageenan,preferably Irish moss; xanthan gums; gum tragacanth; and PVP. It hasbeen found the PVP is stable in the presence of ethyl cellulose, doesnot bleed excessively from the speckles in which it is incorporated as abinder in combination with ethyl cellulose, and lends itself to use toadjust the binding properties of the combination binder, so as to makesuch binder readily adaptable for employment in the same desired totalproportion in a variety of dentifrice formulations, wherein theproportion of ethyl cellulose to PVP may be adjusted accordingly. Asloimportant is the characteristic of the combination binder in theinvented speckles of being sufficiently hard and firm so that duringprocessing the speckles do not dissolve excessively and yet aresufficiently softenable on storage in the dentifrice in which they areincorporated so that they become impalpable by the time the dentifriceis used. They do not soften excessively so as to cause streaking in thetube or during discharge, but by adjustment of the proportion of ethylcellulose to PVP, increasing the PVP, controlled streaking, ifdesirable, may sometimes be obtained.

PVP will usually be of molecular weights in the 30,000 to 50,000 rangeand the PVP preferably employed in the present invention is of amolecular weight of about 40,000. Such a product, which is marketed byGAF Corporation under the trademark Plasdone, as Plasdone K 29-32 and K26-28, has average molecular weights designated by indicated K values,with K-30 being equivalent to about 40,000. PVP is available as a lightcolored powder containing less than 5% moisture, 12.6±0.4% of nitrogen,less than 2 parts per million of arsenic and less than 20 p.p.m. ofheavy metals. It is soluble in cold water and in a variety of organicalcohols, acids, ether-alcohols, ketone-alcohols, chlorinatedhydrocarbons, esters and ketones, but is insoluble in hydrocarbons andsome ethers, chlorinated hydrocarbons, ketones and esters. It iscompatible with various natural and synthetic resins, inorganic saltsand with many synthetic organic detergents, including those commonlyemployed as dental detergents, e.g., sodium higher fatty alcohol sulfateand poly-lower alkoxylated alcohol sulfates.

Although it might have been expected that the best speckles would bemade from the least soluble binder material, it has been found that thecombination of ethyl cellulose and water soluble binder, preferably PVP,as described in this invention, makes speckles of ideal properties,which maintain their individuality and integrity to a satisfactoryextent while being processed and during storage, but which are alsoessentially impalpable during use of the dentifrice in brushing theteeth. If desired, the character of the speckles may be changed, as byvarying the proportions of the ethyl cellulose and PVP, modifying thedegree of ethoxy content of the ethyl cellulose, changing the molecularweight of the PVP and/or by blending with the combined binder othersubstantially water insoluble and/or water soluble binders of knowntypes, some of which are mentioned in the patents previously referredto, the disclosures of which are incorporated herein by reference. Theproperties of the speckles may also be regulated by adjusting theproportions of functional material and the binder, as will be referredto subsequently, and such is an advantage of this invention. Thus,agglomerates may be made which will be stable during processing aftermixing, such as deaerating and filling, yet which will break up rapidlyafter the dental cream is extruded from its container or, if desired,such breaking up may be retarded so that the agglomerates will feelharder and somewhat firmer to the user during brushing of his teeth. Ofcourse, it is normally highly preferable for the speckles to besubstantially impalpable on use, while still maintaining their identityin the dentifrice.

The binder will normally be of particle size like that of the functionalpowdered material of the speckles, especially if the agglomerates are tobe made, at least in part, by compacting of powdered materials. However,because normally the speckles will be made by utilizing an alcoholicsolution of the binder components, the particle sizes thereof are ofrelatively little importance.

The speckles, while sometimes white or colorless and possibly eventranslucent or transparent, or approaching such appearances, may also becolored, normally due to containing a suitable proportion of dye orpigment or a mixture of dyes and/or pigments. Any non-toxic dye orpigment of a suitable color, usually a strong color, such as one of asuitable hue, with a Munsell chroma greater than 4 and a Munsell valuein the 4 to 7 range, may be utilized and in some instances weak colorsor pastels may be satisfactory or desirable. It is usually best toemploy a dye or pigment which is approved for drug and cosmetic use(D&C) or for food, drug and cosmetic use (FD&C). Representative ofsuitable dyes are D&C Reds No's 2, 3, 6, 7, 8, 9, 10, 11, 12, 13, 19,30, 31, 36 and 37; D&C Blue No. 1; FD&C Blues No's. 1 and 2; FD&C RedsNo's. 1, 2 and 3; FD&C Yellow No. 5; cosmetic green oxide; and cosmeticred oxide. Pigments of the foregoing dyes, known as lakes, are alsosuitable for use in coloring the speckles but normally the dyes will bepreferred. The mentioned pigments are often composed of dyes supportedon a finely powdered insoluble carrier, and the pigments are dispersedrather than dissolved in the medium to be colored. The particle sizes ofpigments employed may be within the range previously given for thepolishing agents or may be sized like the binder. Sizes may be finer,e.g., in the 0.01 to 1 micron range. Particle sizes of dyes may besimilar but because they are normally employed in dissolved state, inwater or solvent, preferably being oil soluble and being dissolved inthe appropriate solvent, sizes are not important as long as the powderor particles are small enough so as to make the dye readily soluble inthe solvent chosen.

The speckles of this invention may be made by suitable methods, eitherwet or dry processes. Employing a wet granulation process, the bindercomponents, in dry powder form, are first preferably blended withpolishing agent and dye or pigment, if present, and ethanol orequivalent solvent. Water and/or lipophilic solvent may be present withthe ethanol and a dye or pigment for coloring the speckles may also bepresent. Alternatively, an ethanol solution of the binder may have asuitable dye or pigment and the polishing agent admixed with it.Preferably, the PVP and the polishing agent are pre-mixed, both being inpowder form, the ethyl cellulose is dissolved in alcohol, the solutionis used to "moisten" the powder, and the speckles are made by the "wetgranulation method". The proportions of components employed will be suchas to result in speckles of the desired composition and the proportionof solvent(s) will normally be from 5 to 50% of the mix, preferably 5 to25% thereof.

The production of the dispersion may be by means of a Hobart mixer,Dravo pan, or other suitable mixing device or granulator for wettingpowder(s), and the order of addition of the various components of thedispersion may be adjusted as best benefits the mixing or blendingapparatus employed, although the preferred method described aboveappears to give best results, avoiding gummy overconcentrations ofbinder, and uniformly dispersing the two binders throughout thepolishing agent. A preferred way of producing the speckles is by forcingthe "wetted" mix of polishing agent and ethyl cellulose (with dye orpigment, if present) through a screen having uniform openings, whichusually will be in the range of about 150 to 2,000 microns (about in theNo. 10 to 100 sieve range, U.S. Sieve Series) and the "extruded"agglomerates are then dried, usually either in air or in an oven.Instead of screens, other means, such as pressure extruders, may beemployed for extruding or otherwise pelletizing the mix, after which theparticles resulting are dried. The particles are then classified intodesired size ranges, normally in the No's. 10 to 80 range, preferablyNo's. 40 to 80 and more preferably No's. 30 to 60 (U.S. Sieve Series).Of course, if the wet mass is formed in a Dravo pan the forced screeningor other extruding may be omitted. Generally, when the particle sizesare larger than 2,000 microns (No. 10 sieve) they will be lesssatisfactory for introduction into the oral cavity of a user and whenless than about 177 microns in diameter (No. 80 sieve) they will not beas readily apparent and hence, will not be of as attractive anappearance.

Instead of employing the wet granulation process a dry or sluggingprocess may be utilized, wherein the components of the speckles may bepressed to large tablet size and such tablet may then be broken up, withparticles thereof in the desired size range being separated from theothers. In such tableting process it may be desirable to employ a waterinsoluble lubricant, such as talc, magnesium stearate, calcium stearateor stearic acid, which also helps to facilitate agglomeration.Similarly, such materials and other water insoluble adjuvants may bepresent when wet granulation methods are used. The speckles made arepreferably dry, containing no moisture, but moisture contents of up to10%, e.g., 1 to 5%, may be present without causing any serious adverseeffects on the properties of the speckles.

The proportions in the speckles of water insoluble powdered functionalmaterial, such as dental polishing agent, and the combination binderwill be such that the binder will be the minor component of the specklesand the powered functional material will be the major component thereof(although allowance should be made for the presence of other materialstoo, such as colors and adjuvants). Generally, the dental polishingagent or functional material is from 75 or 80 to 98% of the speckles,preferably 85 to 97% thereof, the binder combination will be 2 to 20% ofthe speckles, preferably 3 to 15% thereof and the colorant will be 0 to5% of the speckles, such as about 0.05 to 1% thereof, all on a drybasis, free of water and ethanol or other solvent. The bindercombination will be one in which the proportion of ethyl cellulose toPVP is in the range of 1:10 to 10:1, preferably 1:5 to 5:1, morepreferably 1:2 to 2:1, and most preferably 1:2 to 1:1, e.g., 2:3.

The dentifrice in which the speckles are distributed may be any suitablesuch product, because in the present invention it acts primarily as themedium for the speckles, maintaining them independent, individual andseparate, while performing its normal dentifrice functions. Opaquedentifrices are useful media for the present speckles but it is highlypreferred that the dentifrice be transparent or translucent and normallybe of a type characterized as a gel. Dentifrices normally comprisewater, humectant, gelling agent, dental detergent and a dental polishingagent, usually with flavoring and/or coloring, too. Among variousfunctional adjuvants are fluorides, stabilizers, anti-caries agents andantibacterial compounds.

The water employed will preferably be deionized water, although citywaters, both soft and hard, may also be utilized. The gelling agent isnormally a water soluble natural or synthetic gum or gum-like material,among which are carrageenan, gum tragacanth, xanthan gum, alginates,alkali metal carboxymethyl cellulose (preferably sodium carboxymethylcellulose), hydroxymethyl carboxyethyl cellulose, polyvinyl pyrrolidone,starch, and hydrophilic colloidal carboxyvinyl polymers, such as thosesold under the trademarks Carbopol 934 and 940. Although various polyolsmay be utilized as humectants those preferred are of 3 to 6 carbon atomsand 3 to 6 hydroxyls per molecule, and those of choice are glycerol andsorbitol. The glycerol is in normal liquid state, generally being about99% or more pure, and sorbitol, normally being a solid, is frequentlyutilized as a 70% aqueous solution thereof (70% sorbitol, 30% water).The three mentioned components may be considered as the mainconstituents of the dentifrice vehicle, in which flavor and detergentmay also be incorporated. Such detergent may include a soap but normallywill be a non-soap synthetic organic surface active agent havingdetersive properties. Preferably such detergent will be of the anionictype, although nonionic detergents are also useful, ampholyticdetergents can be employed, and cationic detergents can be acceptableunder some circumstances.

The preferred anionic detergents are especially useful because theycombine excellent cleaning action and foaming properties. Normally, suchcompounds include hydrophilically and lipophilically balanced moieties,with the lipophilic moiety usually being a higher fatty alkyl or acyl of10 to 18 carbon atoms, preferably 12 to 16 carbon atoms, and thehydrophile being alkali metal, e.g., sodium, potassium, or ammonium orlower alkanolammonium. Suitable such anionic detergents are: the watersoluble salts (normally alkali metal and preferably sodium or potassium)of higher fatty acid monoglyceride sulfates, such as the sodium salt ofthe monosulfated monoglyceride of hydrogenated coconut oil fatty acids;higher alkyl sulfates, such as sodium lauryl sulfate; alkylarylsulfonates, such as sodium linear dodecyl benzene sulfonate; higheralkyl sulfoacetates; higher fatty acid ester 1,2-dihydroxypropanesulfonates; the sodium salts of sulfated polyethoxylated alcohols; andthe substantially saturated higher aliphatic acylamides of loweraliphatic aminocarboxylic acid compounds, such as N-lauroyl sarcosine,and the sodium, potassium and ethanolamine salts of N-lauroyl-,N-myristoyl-, and N-palmitoyl sarcosine, all of which sarcosinecompounds are preferably substantially free from soap or similar higherfatty acid material. Among the nonionic detergents, ethoxylated sorbitanmonostearate, with approximately 20 mols of ethylene oxide per mol;condensates of ethylene oxide with propylene oxide and propylene glycol(Pluronics); polyethoxylated higher fatty alcohols, such as the Neodols(23-6.5 and 45-11, for example); and condensation products ofalpha-olefin oxides containing 10 to 20 carbon atoms, polyhydricalcohols containing 2 to 10 carbon atoms and 2 to 6 hydroxyl groups, andeither ethylene oxide or heteric mixtures of ethylene oxide andpropylene oxide, are useful. Quaternized imidazoyl derivatives, such asMiranol C₂ M, and other Miranols represent useful amphoteric detergentsand the quanternary ammonium halides, such as dimethyl dicetyl ammoniumbromide, represent cationic detergents.

The various polishing agents, which are dispersed in the dentifricevehicle (or vehicle plus detergent and any other adjuvants) are thosepreviously described for conversion to speckle form. Also useful in suchgroup of materials are synthetic finely divided silicas, such as thosesold under the trademarks Cab-O-Sil M-5, Syloid 244, Syloid 266, AerosilD-200, Zeosyl 200 and Zeothix 265, which are normally utilized for onlya small percentage of the polishing agent, normally being no more than 1to 9% by weight of the total dentifrice, and which are useful forthickening or gelling the vehicle and improving the clarity of thedentifrice.

The dentifrices of this invention will normally contain suitableflavoring and/or sweetening materials, Examples of flavors include theflavoring oils, such as those of spearmint, peppermint, wintergreen,sassafras, clove, sage, eucalyptus, cinnamon, lemon and orange, and thesweetening agents include sucrose, lactose, maltose and saccharin.Desirably for fluoride dentifrices there will also be present sodiumfluoride, stannous fluoride, potassium fluoride, potassium stannousfluoride, sodium hexafluorostannate, stannous chlorofluoride and/orsodium monofluorophosphate.

The flavoring materials include various well known essential oils,mainly:terpenes; esters; alcohols; aldehydes; ketones; and otheraromatic substances, many of which emit aromatic odors and fragrances.Because flavor is a simultaneous physiological and psychologicalresponse obtained from the presence of a substance in the mouth anddepends on the senses of taste, smell and feel, with smell often beingof primary importance, it is not surprising that aromatic materials areimportant components of flavors. In the present instances advantage istaken of this fact and of the chemical natures of such materials which,as was previously indicated in the discussion of solubilities of ethylcellulose, permit the ethyl cellulose binder in the present speckles tobe slowly solubilized by the solubilizing substances in the flavoringmaterial, causing softening of the speckles but not causing theirdisintegration. For Example the terpenes, which are hydrocarbons andwhich constitute an important class of perfumery or flavor materials,are good solvents for the ethyl cellulose of this invention, as are manyother flavoring materials, such as those previously named (as flavoringoils) above, and others well known to the perfumery and flavoring arts.By utilizing the flavoring essences in the dentifrice composition tosoften the combination binder of the speckles and thereby make themimpalpable, which is an aim of this invention, it is unnecessary to addanother component to the dentifrice or to the speckles for this purpose.Also, because of the relatively small proportion of flavoring materialnormally present in a dentifrice, with the proportion of the lipophilicpart of the flavor often being lower, a desirable slow softening of thespeckle particles can result, usually due to a relatively low masstransfer rate for the "solvent" material, which transfer rate isespecially slowed due to the gelatinous nature of the dentifrice. Thus,even if some flavoring material at the interface with the specklestarted to soften the ethyl cellulose thereof while the dentifrice wasbeing blended, the flavor solution of ethyl cellulose would soon becomesaturated and this would inhibit further quick dissolving of the ethylcellulose. Still with the passage of the normal time a dentifrice spendsin storage before sale and use, which time will often be at least about2 weeks and sometimes more (with certain dentifrice formulas it isdesirable to allow them to age to improve flavor and productuniformity), the speckles become impalpable, yet remain distinct. Ofcourse, in the above discussion, while references were made to the ethylcellulose binder, it is recognized that the PVP binder is also presentand is soluble in water. Nevertheless, the ethyl cellulose holds thespeckle together in the presence of the PVP until it is solubilized bythe lipophiles in the dentifrice, and the PVP allows less ethylcellulose to be incorporated in the speckles and facilitates thesoftening of the speckles in dentifrices containing lesser proportionsof solubilizing flavoring.

Although it is considered that the flavoring materials, particularly thelipophiles, which exert substantial solvent action on ethyl cellulose,are the most important slowly solubilizing components of the presentdentifrice, the surface active agent component, which includes alipophilic moiety, may also have an appreciable solubilizing effect andby means of its wetting action, may promote mass transfer in adentifrice tube and thereby increase the solubility rate of the ethylcellulose. It is also possible that combinations of other constituentsof the dentifrice, including some of the sweetening agents and vehiclecomponents, will further assist in solubilization of the ethyl celluloseto the extent desired, while not promoting premature softening of thespeckles.

Colorants, such as those previously mentioned with respect to thespeckles, may be employed, normally in lesser proportion, so as toprovide a base which contrasts with the speckles. Various other adjuvantmaterials may be present in the dentifrice, including preservatives,silicones, chlorophyll compounds and ammoniated materials. Normally,when a gel dentifrice is made which is intended to be transparent ortranslucent, the polishing agent chosen will be one having an index ofrefraction closely matching that of the rest of the dentifrice medium.Of course, in such clear gel formulations the amount present ofinsoluble materials which would cloud the gel will normally beminimized. When the pH of the dentifrice is adjusted, and the pH isdesirably within the range of 3 to 10, more desirably from 3.5 to 5 whenstannous ions are present and 4.5 to 7 in the absence of such ions,organic acids, such as citric, malonic, and fumaric acids, may beemployed.

In the dentifrice of this invention a dental polishing agent isuniformly distributed throughout the vehicle of water, humectant andgelling agent, with a dental detergent and the desired proportion offlavor already in it. Then the speckles, which also preferably contain apolishing agent (and often of a different type from that in the body ofthe dentifrice), are uniformly distributed throughout the dentifrice,usually comprising 0.1 to 10% of the dentifrice, preferably 0.5 to 5%thereof, more preferably 1 to 3% thereof and most preferably 1.5 to 2.5%thereof. The dental base will usually comprise: about 5 to 30% water,preferably 10 to 25% and more preferably 10 to 20%; about 20 to 70% ofhumectant, preferably polyol humectant, more preferably 45 to 65%thereof and most preferably 50 to 60% thereof; and about 0.1 to 5% ofgelling agent, preferably 0.1 to 1% and more preferably 0.2 to 0.5%thereof. The humectant is preferably a mixture of glycerol and sorbitolwherein the glycerol content is 5 to 40% of the dental base, preferably20 to 30%, and the sorbitol content is 5 to 50%, preferably 25 to 35%.The preferred gelling agent is sodium carboxymethyl cellulose, and apreferred proportion thereof utilized is about 0.3 to 0.4%. The dentaldetergent content will normally be from 0.5 to 5%, preferably 0.5 to 3%,and a preferred such detergent is sodium lauryl sulfate. The polishingagent in the dentifrice base, exclusive of that in the speckles, isnormally 10 to 40%, preferably 15 to 30% and most preferably 20 to 25%,including Syloid 244 type silicas, which are also employed forthickening. Various other materials, including flavors (usually 0.5 to2%), color, preservatives, sweeteners, and tooth hardeners (fluorides)will normally total no more than 10% of the dentifrice, preferably beingfrom 2 to 7% thereof. Utilizing the proportions of the variousconstituents within the ranges given, with respect to the speckles andthe medium in which they are distributed, results in an attractiveproduct which is stable during storage and in which the speckles areuniformly and attractively distributed.

To prepare the speckled dentifrice, after first producing the speckles,is comparatively simple but an important consideration is that minimalmechanical agitation should be employed so as to prevent or delay anydisintegration, softening and solubilization of the speckles in thedentifrice. It is considered that lipophilic materials and solventspresent, such as those in flavoring oils, will slowly solubilize ethylcellulose, but not to an objectionable extent in the absence of vigorousagitation in processing. If the dentifrice is at an elevated temperatureduring such mixing, normally due to manufacturing limitations inprocessing, it is even more important to minimize agitation. However,with the ethyl cellulose-containing binders that are used in themanufacture of the speckles, manufacturing restrictions may be lessstringent, but care should still be exercised. Suitable equipments fordistributing the speckles throughout the dentifrice include Banbury ordough mixers operated at low speeds but other gently operated blendersmay also be used providing that mixing is controlled so as to preventsubstantial breakdowns, dissolvings or disintegrations of the speckles.Normally mixing blade speed will be on the order of one to five r.p.m.and mixing will last from one to five minutes. After completion of theblending the dentifrice is deaerated and filled into containers, such asresilient or collapsible tubes. If vacuum is employed during mixingoperations deaeration may be omitted.

The manufacturing method described in the preceding paragraph is astandard method for making speckled dentifrice, with the exception ofthe processing of the present speckles in such dentifrice and therequirement for the presence of slowly solubilizing lipophilic materialin the base of the dentifrice, together with the speckles bound togetherby PVP-ethyl cellulose. However, recently new methods have been inventedfor facilitating blending of the speckles into the dental gel bodywithout excessive agitation. Such methods and the apparatuses by meansof which they are practiced are the inventions of Edward J. Gibbons andJohn Smith, respectively, and are the subjects of patent applications tobe filed by them on the same date as the present application. In suchmethods the dentifrice is fed through an orifice to form a falling,curving ribbon onto which speckles are uniformly dropped at a constantrate, after the speckled gel dentifrice is transported to fillingequipment by means of a positive displacement variable walled pump, suchas one of the Moyno type.

Although normal collapsible aluminum tubes with capped dispensingopenings, through which the dentifrice may be squeezed, are mostcommonly employed, it is often preferred to make the packaged dentifriceby utilizing a deformable tube of clear or translucent synthetic organicpolymeric material, such as polyvinyl chloride, polyethylene,polyvinylidine chloride or similar material through which the attractiveappearing speckled dentifrice may be viewed.

In FIG. 1 there is shown a plan view of the clear walled container 11,which is made of transparent polymeric material (PVC), including body13, shoulder 15, threaded neck 17 and cap 19, with the cap having beenremoved from the tube. As illustrated, some of the dentifrice 21 isbeing dispensed from tube 11 through neck 17 onto the bristles of atoothbrush 12. In the dentifrice there are clearly shown inventedspeckles 23 in the continuous dentifrice medium 25. It is noted thatsuch speckles are initially impalpable although they are easily visible.During toothbrushing they break down into smaller entities ofessentially the same sizes as the component polishing agent. Of course,the speckle polishing agent acts together with that in the dental gel tohelp clean and polish the teeth.

The following examples illustrate but do not limit the invention.Throughout the specification, including the working examples, and in theclaims, all parts are by weight, unless otherwise indicated.

EXAMPLE 1 (Actual)

95 Parts of calcined alumina (Microgrit WCA 9F) of particle sizes in therange of 0.5 to 10 microns and an average particle size in the range of3 to 5 microns are blended with three parts of powdered polyvinylpyrrolidone, obtained from GAF Corp., and marketed by them under thedesignation Plasdone K-29-32. Two parts of ethyl cellulose (10centipoises), of the physical characteristics described previously inthe specification and in powder form, are dissolved in five parts ofethanol (95%) and the PVP-alumina blend is mixed with the solution in aHobart mixer. Mixing is continued for about four minutes until the blendis uniform, after which the mix is forced through a No. 10 (U.S. SieveSeries) screen, and the "extruded" material is oven dried for one hourat 60° C. The dried agglomerates are then screened through a No. 30screen and the cut that rests on a No. 60 screen, the dried specklescomprising the calcined alumina, PVP and ethyl cellulose, is collected.The speckles produced are of angular shapes, with the ratios of maximumlength to maximum width usually being within the 1 to 2 range and mostof the particles being of such a ratio within the 1.1 to 1.5 range. Theangularity of the particles may be a factor in making the dentifrices soattractive in appearance, at least for some consumers.

A transparent (or translucent) dentifrice base (all components exceptspeckles) is made of the following formula:

    ______________________________________                                        Component                Parts by Weight                                      ______________________________________                                        Glycerol (99.3% pure)    25.00                                                Sodium carboxymethyl cellulose                                                                         0.35                                                 Sorbitol (70% aqueous solution)                                                                        39.04                                                Polyethylene glycol 600  3.00                                                 Water                    3.00                                                 Sodium saccharin         0.25                                                 Sodium benzoate          0.50                                                 Blue dye (FD & C Blue No. 1, 1% aqueous                                                                0.20                                                 solution)                                                                     Sodium monofluorophosphate (1 to 60 microns)                                                           0.76                                                 Silicon dioxide (Zeo 49) 18.00                                                Synthetic silica (Syloid 244)                                                                          5.50                                                 Sodium lauryl sulfate    1.20                                                 Flavor (spearmint, peppermint, wintergreen,                                                            1.20                                                 clove, etc., as desired)                                                                               98.00                                                ______________________________________                                    

Two parts of the described speckles, with particle sizes -30 +60 (U.S.Sieve Series), are gently blended in a slow moving mixer (about twor.p.m.) with 98 parts of the described dentifrice base, after which themix is deaerated and automatically filled into capped collapsible tubeswhich are then sealed. During the mixing, dearation and tube fillingsteps the speckles, which are substantially evenly distributed throughthe dentifrice, remain discrete, independent and undissolved in thedentifrice base so that when the tube is opened, after filling, andpreferably, after storage for about a month, and the dentifrice issqueezed through the discharge opening thereof, the speckles appear tohave retained their initial integrity, contrasting with the bluish gel,in which they appear to be substantially evenly spaced, with no clumpsor overconcentrations being readily apparent. When the product isevaluated immediately after filling, and without being stored, thespeckles are palpable but, upon storage before use, for periods from twoweeks to a year or more, are sufficiently softened, as by solubilizationof the PVP by the moisture present and solubilization of the ethylcellulose by the flavoring oil, both solubilizations apparentlysometimes being with the aid of the dental detergent or other surfaceactive agent that may be present, and sometimes assisted by othercomponents too. The "solubilized" speckles appear distinct and are not"smeared"; yet they are satisfactorily impalpable. During toothbrushingwith the dentifrice the speckle particles are readily reduced in size,are not irritating to gingiva, and are readily dischargeable from theoral cavity on completion of brushing.

Although the presence of the anionic detergent in the dental base may beof assistance, it is thought that the controlling component of such baseis the 1.2% of flavoring agent present. A proportion of such an agent ora mixture thereof from 0.5 to 2%, preferably 0.8 to 1.5%, of which atleast half is normally active as a solvent for ethyl cellulose, isdesirable for best speckle dispersions, and the flavor will usuallyinclude over 50% and often over 80% of solubilizing hydrocarbons,esters, alcohols and aldehydes.

When the proportion of flavor in the dental gel base is decreased to0.6%, half that of the above formula, the PVP-ethyl cellulose bindersystem for the speckles still is effective and they are satisfactorilyimpalpable on storage. It is also effective when the flavorconcentration is varied to 0.3%, 0.9% and 1.5%. However, the greaterproportions of flavor (and/or other lipophile solvents) may causesomewhat earlier solubilization than preferred, in which case theproportions of PVP and ethyl cellulose will preferably be varied, to 2parts PVP and 3 parts ethyl cellulose, for example. Similarly, if thepalpability of the speckles should increase to more than desired theymay be made softer by increasing the PVP proportion, e.g., to twice theethyl cellulose. The concentrations of speckles and the sizes thereofmay be changed, within the ranges previously given. Also, others of thematerials previously listed may be substituted for the alumina polishingagent, including other types of water insoluble functional substances.

The manufacturing method described for the dentifrice, in which thespeckles are dispersed in the body of the gel, is one in which themixing operation should be watched to make sure that the speckles arenot disintegrating and, at any sign of this happening mixing should behalted and, providing that the dentifrice appearance is notsignificantly adversely affected, usually by being made unacceptablycloudy, filling of the tubes should be undertaken promptly. Instead ofemploying the described mixing method it will often be preferable toutilize the Gibbons or Smith methods, previously referred to herein,wherein a regulated even "fan" of speckles is deposited by means ofgravity on a continuously falling extruded ribbon of gel, to which thespeckles adhere, so as to obtain uniformity of distribution of thespeckles in the dentifrice. With respect to such processes andapparatuses the specifications and drawings of such patent applicationsare hereby included by reference.

When the speckled dentifrice of this invention is packed in acollapsible aluminum tube the speckles in the dentifrice are not visibleuntil discharge from the tube but at that time they are maintaineddiscrete in the toothpaste extruded and impart to it an attractive anddistinctive appearance. However, when instead of the normal aluminumtubes one employs resilient transparent tubes, such as tubes ofpolyvinyl chloride or other suitable polymer, the speckles can be seenthrough the tubes and through the transparent gel dentifrice base, andtheir movements, on discharge, can be observed. This provides anadditional aesthetic benefit and helps to make toothbrushing moreinteresting, at least for children. Additionally, the functionalspeckles act as a reminder to the person using the dentifrice of thepresence of polishing agent or other functional constituent in thedentifrice and thereby help to remind him of the importance of brushingso that such component may be effective.

The formula given above is one for a gel dentifrice in which the normal41.04% of sorbitol solution had been reduced to 39.04% to allow for theintroduction of the 2% of speckles. The effect of this change in theformulation is to maintain the percentages of the other dentifricecomponents the same as in an unspeckled product, with the exception ofthe major component, the sorbitol solution. It is considered that withother variations in the contents of speckles in such dentifrices suchprocedure for modifying the formula may continue to be followed.However, it is also feasible to start with the initial gel formulation,e.g., containing 41.04% of sorbitol solution, and reduce each of thecomponents proportionately to allow for the introduction of the desiredpercentage of speckles.

In a variation of the above described experiment 1% of ultramarine bluepigment may be employed in place of 1% of the Microgrit, so that thespeckles are of a definite blue coloration. In place of the describedproportion of ultramarine blue one may use 0.5 to 2.0% of that pigmentor mixtures of pigment(s) and polishing agent(s) of proportions from1:10 to 10:1 may be used. Alternatively, about 0.1 to 1% of any suitablewater insoluble (or oil soluble) dye may be employed. In such cases thedye solution may be omitted from the dentifrice base formula or may bepresent, providing enough contrast between the speckles and the base isobtainable.

Of course, the various components of the formula may be replaced byothers, such as those previously described, and useful products willalso be obtained. For example, the different mentioned pigments and dyesmay be employed, the sodium lauryl sulfate may be replaced by sodiumethoxylated higher fatty alcohol sulfate or sodium hydrogenated coconutoil fatty acids monoglyceride monosulfate, and the polishing agents maybe replaced by dicalcium phosphate dihydrate and/or dicalcium phosphate(anhydrous) or mixtures thereof. Proportions of the various componentsmay be modified ±10%, ±20%, and ±30%, so long as they are maintainedwithin the ranges previously recited, and the results are satisfactoryproducts of similar properties, although those of the proportions ofthis example are preferred.

EXAMPLE 2 (Actual)

75 Parts of anhydrous dicalcium phosphate and 15 parts of dicalciumphosphate dihydrate, both having average ultimate particle sizes ofabout 4 microns, are mixed with 5 parts of ethyl cellulose, 5 parts ofPVP and 10 parts of ethyl alcohol in a Hobart mixer. Alternatively, andpreferably, ethanol and ethyl cellulose may be premixed and then may beadmixed with a previously made blend of the dicalcium phosphates withPVP. The mass formed is forced through a screen having uniform openingsof 2,000 microns and is then oven dried for one hour at 60° C. The driedagglomerates are then screened through a screen having uniform openingsof 420 microns and those agglomerates which do not pass through ascreeen having uniform openings of 177 microns are collected. Next, theagglomerated functional particles resulting are mixed with a dentifricebase of the formula given in Example 1, with the exception that thepolishing agent in such base is replaced by sodium aluminosilicate, suchas that marketed under the trade nmae Zeolite 4A.

In variations of this formula there may be substituted for the polishingagent of the speckles, hydrated alumina having an average particle sizeless than about 10 microns, calcium carbonate having particlessubstantially all of which are less than about 7.4 microns in diameter,insoluble sodium metaphosphate having an average particle size of about5 microns (all such sizes being ultimate particle sizes), or aproportion of the polishing agent may be replaced by sodiummonofluorophosphate of similar particle sizes.

The dentifrices of this example are speckled, transparent or translucentproducts and are aesthetically pleasing in appearance. The visibleparticles of the agglomerated polishing agents (for which otherfunctional insoluble materials may be substituted in whole or in part)are substantially uniformly dispersed in the dentifrice base as visiblyseparate entities and are also essentially impalpable upon use, afterstorage. When the transparent gel is made opaque, as by incorporationtherein of an opaque polishing agent, the speckles are still visible atthe surface of the extruded dentifrice but the effect is not asstriking.

EXAMPLE 3 (Theory)

The functional polishing agent constituent of Example 2 is replaced by amixture of ten parts of anhydrous dicalcium phosphate and 90 parts ofcalcium carbonate, with the same total proportion of polishing agentbeing employed; otherwise the same procedure is followed. The productsresulting are similarly satisfactory in functional effects and areaesthetically pleasing in appearance. Similar results are obtained whendifferent mixtures of the disclosed polishing agents are substituted forthe present mixture in the speckles, and when proportions thereof arevaried.

EXAMPLE 4 (Theory)

Instead of dissolving the ethyl cellulose and PVP in ethanol or othersuitable solvent, agglomerates like those of Example 3 are made byblending the polishing agent, PVP and ethyl cellulose, sometimes with areduced proportion of ethanol present, to form a powder blend. Suchblend is compressed in a rotary tablet press to form slugs, about 6 mm.thick and 25 mm. in diameter. The slugs are then granulated in anoscillating granulator to form smaller particles, preferably such aswill pass through a No. 40 screen and rest on a No. 60 or No. 80 screen.This technique for making the speckles may also be applied to any of thespeckle formulas given in the preceding examples. Although the bindingeffects of the PVP and ethyl cellulose might not be as great, theproducts of this example are also satisfactory for incorporation indentifrices to contribute their aesthetic advantages and functionaleffects. If the binding effects of the PVP and ethyl cellulose in theforegoing formulas are not sufficient, the proportions thereof presentmay be increased, sometimes up to 100 or 200%, but such increasesinvolve additional expenses and therefore the "wet" method, in whichsolutions of PVP and ethyl cellulose in ethanol or other suitablesolvents are employed, is often preferred.

With respect to all the preceding examples, the manufacturer will takecare to adjust the formulation to obtain the desired type of speckle, ofthe desired solubility or "resistance to solubility" in the dentifrice.This may be accomplished by choosing the binders, particularly the ethylcellulose, in accordance with the amount of solubilizing materials,especially flavoring agent (and detergent and any other lipophile)present. For example, the medium ethyl cellulose previously mentionedmay be employed when larger proportions of flavoring agent are present,with the standard ethyl cellulose being used for lesser amounts of theflavoring agent (and other lipophiles). Mixtures of the two and mixtureswith ethyl celluloses of other characteristics may be made to obtainintermediate properties for the present combination PVP-ethyl cellulosebinders. Also, the nature of the lipophilic portion of the dentifricebody may be adjusted, where possible, so as to increase or decreasesolubilizing effects so that the suspended speckles behave in thedesired manner, resisting early disintegration but becoming impalpablethereafter.

EXAMPLE 5 (Theory)

In the preceding examples, the polyvinyl pyrrolidone, the water solublebinder portion of the combination binder, is partially replaced (50) orentirely replaced by the following water soluble binders: gum acacia,gelatin, corn starch, sodium carboxymethyl cellulose, sodium alginate,polyvinyl alcohol, carrageenan, xanthan gum and gum tragacanth. Thespeckles made, when incorporated in gel dentifrices like thosepreviously described in these examples, sufficiently retain theirindividuality and integrity during processing but become impalpable onstorage in the dentifrice, while still retaining their original shapes,in the same manner as the speckles made with PVP-ethyl cellulosecombination binders. However, it is considered that the PVP-ethylcellulose combination binder is generally superior in its combination ofdesirable features, including processing stability, compatibility withdentifrice components, and conversion from palpability to impalpabilitywithout loss of speckle integrity and without significant change inappearance.

EXAMPLE 6 (Actual) (Comparative Example)

Speckles of various compositions are compared to those of this inventionthat are based on ethyl cellulose and PVP. The invented speckles aremade in generally the manner as described in Example 1, by the wetmethod, and the speckle formula includes 95% of calcined alumina, 2% ofethyl cellulose and 3% of PVP with such materials being the same asthose used in Example 1. The speckles of the comparative experiments arealso made by the wet method, except for one type, which will beindicated, which was made by the dry of "slugging" method of Example 4.

The speckles were tested by weighing out 100 milligrams of each type,separately placing them on glass slides, adding to each four drops ofwater, covering each slide with another slide, and noting the time ofphysical change and the type of physical change in the granules. When 2%of sodium carboxymethyl cellulose is employed as the binder the speckleslose integrity within fifteen seconds, which is also the case with thespeckles bound with 2% of hydroxypropyl methyl cellulose, but that takestwo minutes. Speckles made with a binder comprising 2% of methylcellulose and 3% of PVP soften, swell and lose integrity after about twominutes and when 5% of PVP is employed as the sole binder speckles madewith it soften after eight minutes. When the binder is 1% of methylcellulose (400 centipoises) the speckles lose integrity after a littlemore than five minutes and when the binder is changed to 10% ofpolyethylene glycol 6,000, with 1% of magnesium stearate, with thespeckles being made by "slugging", they lose integrity after nineteenminutes. The "control" speckles of this invention, including 2% of ethylcellulose and 3% of PVP, when subjected to the same test, are stillintact after over six hours.

The results of this test clearly indicate the importance of the presenceof ethyl cellulose with a water soluble binder, preferably with PVP.

The invention has been described with respect to various illustrationsand embodiments thereof but is not to be limited to these because it isevident that one of skill in the art with the present specificationbefore him would be able to utilize substitutes and equivalents withoutdeparting from the invention.

What is claimed is:
 1. Functional agglomerated speckles, forincorporation in dentifrices, which comprise agglomerates of a waterinsoluble powdered functional material, a water insoluble, ethanolsoluble ethyl cellulose binder, and a water soluble binder.
 2. Specklesaccording to claim 1 wherein the water insoluble powdered functionalmaterial is a dental polishing agent which constitutes a majorproportion of the speckles, the water soluble binder is polyvinylpyrrolidone (PVP), and the combination binder, including the ethylcellulose and the PVP, is a minor proportion of the speckles. 3.Speckles according to claim 2 wherein the ratio of ethyl cellulose toPVP is within the range of 1:10 to 10:1 by weight.
 4. Speckles accordingto claim 3 wherein the water insoluble dental polishing agent isselected from the group consisting of dicalcium phosphate, tricalciumphosphate, insoluble sodium metaphosphate, alumina, silica, magnesiumcarbonate, calcium carbonate, calcium pyrophosphate, bentonite andzirconium silicate, and mixtures thereof, of particle sizes in the rangeof 0.5 to 20 microns, the speckles are of sizes to pass through a No. 10U.S. Sieve Series sieve and be retained on a No. 80 Sieve, and in thespeckles the ratio of ethyl cellulose to PVP is within the range of 1:5to 5:1.
 5. Speckles according to claim 4 wherein the dental polishingagent comprises 80 to 98% of the speckles, and in the binder, the ratioof ethyl cellulose to PVP is within the range of 1:2 to 2:1.
 6. Specklesaccording to claim 5 which comprise 85 to 97% of the dental polishingagent and 3 to 15% of the combination binder, which are of such particlesizes that they pass through a No. 30 U.S. Sieve Series sieve and areretained by a No. 80 sieve, and in which the ratio of ethyl cellulose toPVP is within the range of 1:2 to 1:1.
 7. Speckles according to claim 6which comprise 90 to 97% of calcined alumina, as the dental polishingagent, and 3 to 10% of the combination binder, and in which the ratio ofethyl cellulose to PVP is about 2:3.
 8. A method of making speckles forincorporating in dentifrices which comprises mixing a powdered watersoluble binder with a water insoluble functional powdered material,dissolving water insoluble ethyl cellulose in a volatile solvent to makea solution, moistening the mix of water soluble binder and functionalmaterial with the solution of ethyl cellulose, compacting the moistenedpowder, converting it to particulate form, drying the particles andcollecting those that pass through a No. 10 U.S. Sieve Series sieve andare retained on a No. 80 sieve.
 9. A method according to claim 8 whereinthe water insoluble functional powdered material is a dental polishingagent selected from the group consisting of dicalcium phosphate,tricalcium phosphate, insoluble sodium metaphosphate, alumina, silica,magnesium carbonate, calcium carbonate, calcium pyrophosphate, bentoniteand zirconium silicate, and mixtures thereof and is of particle sizes inthe range of 0.5 to 20 microns, the water soluble binder is PVP, and thevolatile solvent is ethanol, compacting and converting of the moistenedpowder to particulate form is effected by forcing it through a screen orsimilar sizing device and the dried particles collected are those thatpass through a No. 30 U.S. Sieve Series sieve and are retained on a No.80 sieve.
 10. A method according to claim 9 wherein the proportions ofdental polishing agent and combination of binders in the moistenedpolishing agent and in the product are, on a solids basis, 80 to 98% ofdental polishing agent and 2 to 20% of binder, the moistened powder iscompacted and converted to particulate form by passing through a screenof a size within the No. 10 to 60 U.S. Sieve Series range, the materialresulting is dried at an elevated temperature to drive off the ethanol,and particles of the dried product in the No. 30 to 60 range arecollected.